Then he made himself lunch, which consisted of coffee and open sandwiches, and sat in the garden, where he was typing up the notes of his conversation with Pastor Falk. When that was done, he raised his eyes to the church.

There's nothing more satisfying than preserving food. In times of plenty - a glut of cucumbers, boxes of overripe tomatoes, a whole side of salmon - there is joy to be found in keeping some back for later months. Salt, sugar and vinegar are my constant allies; they've been by my side during bouts of chutney making at Christmas-time, helped me keep the taste of a trip to Normandy alive with a very special plum jam and ensure that I can extend the radish season each year (at least in my house).

More than anything else, preserving food feels like a genuine link to previous generations - I'm doing what my great-great-great-grandmother's generation would have done, before refrigeration or Sainsburys Local or Deliveroo. One of my very favourite examples of old-school food preservation is gravlax; a Scandinavian method of preserving fatty fish with salt and sugar. Originally buried underground, it is now more commonly buried under a mountain of dill. I could eat it on/with pretty much anything, and am still rationing the leftovers from this batch. When at Billingsgate a couple of months back, I couldn't walk past a side of salmon, thrown unceremoniously into a garbage bag by a giant man with an enormous beard. It's served me well; sliced up into fillets that have stocked my freezer for months, and allowing me to fulfil a long held desire: curing my own salmon. Not bad for £12.

There are lots of other (less murder-y) books I could have used here, but I immediately thought of this. I lost count of the number of open sandwiches Mikael Blomkvist sat down to eat - my memories of the book are definitely more focussed on the sandwiches and coffee (I've worked hard to leave other particularly vivid memories behind).

EquipmentLarge flat dish that will fit in your fridgeSecond dish to fit on top, and something heavy to put in it (I used tins of tomatoes)Mortar and pestleCling filmTwo large jarsMandolinKnife and chopping boardMeasuring jug

1. If you've bought a whole side of salmon, you're going to need to select which part to turn into gravlax. You'll need two equal(ish) sized pieces that have a similar thickness, otherwise you'll end up with bits that are over- or under-cured. Leave the skin on, but do de-scale if this hasn't been done already.

2. A fishmonger should be able to tell you whether you're buying sushi-grade salmon - the type you can confidently eat raw. If you're not sure, then freeze it for 24 hours before adding the cure. This will kill any parasites. I managed to freak myself out, forget what the guy at Billingsgate had said, and froze mine just in case. It still tasted glorious.

3. Defrost your salmon (if you've frozen it) and place both pieces skin side down on the bench. In the mortar and pestle, pummel your pepper, then add the salt and sugar and mix thoroughly. Chop the dill.

4. Place half of the dill on top of one of the pieces of fish, then pack the salt, sugar and pepper mix on top. Cover with the other half of the dill, then place the other piece of fish (skin side up) on top. Place the whole dill/fish sandwich into the flat dish and cover with cling film. Place another dish on top, push down, and weigh down with tins. Place in the fridge.

5. The gravlax will need to sit with its cure for 48 hours. Turn it every 12 hours, draining away the liquid, then replacing the cling film and weight each time. In terms of timing, turning it before and after work worked for me. You don't have to follow the 12 hour rule religiously - I was home a bit late one night, but it survived (full disclosure: I was a little full of gin, and nearly forgot about it completely, but I reckon it would have been OK if I had).

6. When your gravlax is ready to eat, prepare the cucumber pickle. Slice the cucumbers very finely (a mandolin is handy here, but not compulsory). Dissolve the sugar and salt in the vinegar. Layer the cucumber slices, dill fronds and coriander seeds in the jars, then pour the vinegar mixture to the top. Turn the jar over a couple of times to ensure the vinegar has reached the bottom. Leave for at least 30 minutes to pickle slightly, though the leftovers will be great too, for at least a couple of weeks.

7. To serve, scrape the cure off the salmon. Slice perpendicular to the bench, lifting each slice away from the skin. Slice it to your taste - I like it much thicker than it usually comes when packaged. Butter slices of the bread, top with salmon, the cucumber and a dribble of the pickling juice. Serve with coffee.